Problem: $ \left(\dfrac{16}{25}\right)^{-\frac{1}{2}}$
Answer: $= \left(\dfrac{25}{16}\right)^{\frac{1}{2}}$ Figure out what goes in the blank: $\Big(? \Big)^{2}=\dfrac{25}{16}$ Figure out what goes in the blank: $\Big({\dfrac{5}{4}}\Big)^{2}=\dfrac{25}{16}$ So $\left(\dfrac{16}{25}\right)^{-\frac{1}{2}}=\left(\dfrac{25}{16}\right)^{\frac{1}{2}}=\dfrac{5}{4}$